Die cushion unit



July 10, 1 R. E. WISSMAN DIE CUSHION UNIT 3 Sheets-Sheet 1 Filed July 22, 1955 P" e "F E\ N A M S .6 W

ATTORNEYS July 10, 1956 R. E. WISSMAN DIE CUSHION UNIT 5 Sheets-Sheet 2 Filed July 22, 1955 INVENTOR. REUBEN E. WISSMAN BY g #7 Z ATTORNEYS July 10, 1956 R w 5 2,754,110

DIE CUSHION UNIT Filed July 22, 1955 5 Sheets-Sheet 3 .4 j y w I I 58 F i: 5 i I f ii: 5 1) I6 56- /7s /52 GD 20 A g #6 WE so i FIG-5 INVENTOR. REUBEN E. WISSMAN BY 7%;M

ATTORNEYS United States Patent um CUSHION Reuben E. Wissman, Minster, Ohio, assignor to The Minster Machine Company, Minster, Ohio, 2 corporation of Ghio Application July 22, 1955, Serial No. 523,686 Claims. (61. 267-4 This invention relates to die cushions, particularly to die cushions for mechanical presses.

Most presses of any substantial size are adapted for having associated therewith a die cushion for the purpose of adapting the press for drawing work members to various shapes and suitable die sets. A die cushion of this nature is essentially a unit which offers a predetermined resistance to downward movement of a portion of that part of the die set that is mounted on the press bed. For example, the die may comprise a bottom which is to yield downwardly as the drawing operation proceeds and the thrust which resists this downward movement is created by the die cushion which usually bears a platen that is engaged by rods extending from the die bottom downwardly.

Die cushions of the nature referred to are naturally subjected to some side loading during operation and for this reason must be guided during theirmover'nent. Here'tofore, it has been a problem to be certain that the guideways for the die cushions were properly lubricated since the location of the unit makes it difficult to supply the lubricant properly and also, it is easy to overlook the die cushion in its hidden location. This has led to considerable difiiculty, particularly in high production shops where the utmost in production is desired and where the presses are maintained in operation substantially continuously during the working day. For example, with improperly lubricated guideways, the die cushion platen can bind on one side and tilt leading to extreme wear and possible damage to the cushion or die. This possibility is enhanced by side loading'which is often present. 0

Having the foregoing in mind, it is a particular object of this invention to provide a die 'cushion 'ar'rang'ernent for a press, such as a mechanical press, in which the guideways for the die cushion are maintained adequately lubricated at all times without requiring any "attention whatsoever. 7

A still further object of this invention is the provision of a die cushion unit which can be installed as a 'unit in 'a press and which can be removed as a unit from a press thereby greatly simplifying the conve'rsion of a press to andfrom die cushion operation and also making it a simple matter to provide an existing press with a die cushion unit.

A still further object of this invention is the provision of a die cushion assembly for "a press inwhich the Lubricant supply is protected against contamination atall times.

A still further object is the provision 'o'f a 'die'eush-ien arrangement of the nature referred to having 'an integral lubricating system in which the guideways for the die cushion are continuously lubricated by lubricantssu'pplied thereto automatically on each'cycle of operation of the press.

These and other objects and advantages will become more apparent upon reference to the following des'c-riptiontaken-in connection with the drawings in whichz Figure 1 is a perspective view showing a press adapted for being provided with a the cushion unit according to my invention; 7 v Figure 2 is an enlarged perspective'view of the bed of e press .partly broken away showing the die cushion unit therein and with the protective top plate removed therefrom;

Figure 3 is an enlarged vertical sectional view through the bed of the press showing the construction of the die cushion unit including the pumping means of Figure 4 in detail and in operative position;

Figure 4 is an enlarged vertical sectional 'view at one corner of a die cushion unitshowing a further embodiment of the pumping means associated with the die cushion unit; and

Figure 5 is a vertical section of another point about the die cushion showing a drain from a drain groove in a top plate of the die cushion unit of Figure 2.

Referring to the drawings somewhat more specifically, the press shown in Figure 1 shows a frame 10 in which there is a vertically reciprocal platen 12 actuated 'by a crankshaft from a power source drivingly connected with a flywheel 14.

The frame 10 comprises a bed portion 16 which has a vertical recess in which there is mounted the die cushion unit according to this invention which is generally indicated at 18.

As will be seen in Figures 2 and 3 the bed 16 of the press has guideways formed about the inner Wall of the recess therein which may take the form of bronze Wear strips 20. The bronze wear'strips 20 are adapted for engagement by the slide members 22 which maybe formed on or affixed to the outer periphery of platencarryi-n'g cylindermember '24 which has its upper end closed and its lower end open and is in the general form of a cylinder. The platen is indicated by the numeral 25 Cylinder 24 comprises the movable member of'theidie cushion unit. Thelower open end of cylinder 24 (Figme 3) is adapted for receiving the stationary hollow plunger member 26 'which rests on machined locating pads 28 projecting upwardly from the bottom of the rece ss in-the press bed 16.

There is a seal member at 34 between the upper end of plunger 26 and cylinder 24 to prevent leakage of pressure fluid from the cavity formed thereby.

The die cushion illustrated is adapted for being urged upwardly by a supplyo'f air under pressure to thespac'e between guide26 and cylinder 24 and this may 'be-accomplished by 'providing'hollow memberBdwhich Lprojects upwardly from the bottomwa ll of the bed '16 and is adapted for entering an aperture 38 in the bottom Wall 32 of guide 26. LA seal "may be effected between member 36 and guide 26 by the resilient O ring "40 or some other suitable sealing member. Aconduit 42 supplies air under pressure throug'hmeniber '36 to the inside of cylinder24.

'It will be noted that ring means '30 carried on't'he bottom of cylinder -24-is operable as -a stop to'limit'the upper 'movement'of "cylinder 24 by abutting shoulder '44 on'guide 26. The region 45 above shoulder "44 .s'lidably fits the herein the cylinder and assists guiding-"the cylinder during its movement.

According to the present invention, means are provided for maintaining a supply of lubricant to the guideways for the die cushion and 'this takes the form era pumping mechanism generally indicated at in Figure 3 whichis operable on-each'strokeof .the die cushion to supply lubricant to the guideways.

As will be seen in Figure '3, the pumping means 46 comprises "a "reciprocal plunger portion made up of a head 48 and-a tub'e '50 alfixed thereto which extends downwardly from the upper end of cylinder 24 externally of the skirt thereof (see Figure 2). The tubular portion 50 extends into a somewhat larger tube 52 that is fixed in the bottom wall of the recess in the press bed and extends vertically upwardly therefrom.

Pumping action is bad by vertical reciprocatory movement of cylinder 24 of the die cushion by providing the lower end of tube 52 with an upwardly opening check valve 54 and by providing the lower end of tube 50 with a corresponding upwardly opening check valve 56.

A seal which may take the form of the resilient O ring 58 etfects a fluid seal between tubes 50 and 52 adjacent the bottom of tube 50 so that when the die cushion cylinder moves upwardly a suction is created in the lower part of tube 52 that will draw lubricant from the sump 60 into which valve 54 projects into the lower end of tube 52; whereas, upon downward movement of the die cushion cylinder, this lubricating fluid will be displaced upwardly through check valve 56 to flow through tube 50 and head 48 and out the upper open end of the said head. A drain plug for the lubricant is indicated at 61.

Reference now to Figure 2 will reveal that the upper open end of the said head 4-8 communicates with a channel 62 formed about the upper surface of cylinder 24 of the die cushion (Figure 2). This channel 62 is intersected by other channel means 64 leading toward the guideways for the die cushion and the last mentioned channel means are connected via passages 66 with the outer surfaces of the guide members 22 which engage the guiding wear plates 20. Each guide member 22 may advantageously be provided with an oil groove 68 so that lubricant supplied to the guide surfaces will be distributed thereover.

The lubricant so supplied the guide surfaces for the die cushion, as it drops therefrom, will fall into the recess in the bed and may be collected by any suitable sort of channel means 70 therein and delivered to sump 60 through a protective screen 72.

Also leading from channel 62 is a downwardly extending channel 63 which is intersected by a bore 65 leading, as will be seen in Figure 3, to spacing 69 on the inside of the cylinder 24 for providing lubricating fluid thereto. On the opposite side of the cylinder 24 from the opening of bore 65 is a bleeder hole 67 opening to the outside of the cylinder, and from which air entrapped between the cylinder 24 and the outside of guide 26 is expelled, and also through which the lubricating fluid supplied to the cylinder can leak to the recess in the press bed, thereby providing for circulation of the lubricating fluid through the cylinder. It will be evident that the oil supplied to the inside of the cylinder will be carried thereby to the packing ring 34 when the cylinder reaches its uppermost position whereby the packing 34 is maintained wet with the lubricating fluid at all times and thus is in condition to maintain a film of oil within thecylinder and efiectively to seal against leakage of air under pressure between the cylinder and guide.

It will be apparent that a substantial quantity of lubricating fluid could be retained within the recess in the press bed and that this fluid will continuously circulate to all wearing surfaces associated with the die cushion that it is desired to protect against wear.

According to this invention, the lubricant supply is advantageously protected against contamination as, for example, by drawing fluids, by mounting a top plate 74 on the upper end of the cylinder member, and which top plate is provided with an annular drain groove or channel 76 which may be drained by the telescoping drain tube arrangement having portions 78 and 79 (Figure that extend out the bed so that any drawing fluids or other contaminating liquids that may reach top plate 74 during the operation of the press will be prevented from contaminating the lubricant supply in the press bed.

It will also be evident that the die cushion unit as it is illustrated in the present application is adapted for being removed from the press bed merely by lifting it vertically upwardly from the recess in which it is located and that the die cushion can be inserted in the press bed in the same simple manner merely by properly orienting the parts of the pumping means 46 and lowering the die cushion unit downwardly into the press bed until it comes to rest on the machined supporting pads 28.

It Wlll be evident that existing presses having recesses in the bed could be provided with a die cushion according to the present invention merely by providing the recess in the bed with the wear plates 20, the hollow air supply member 36, and the stationary elements of the pumping means referred to.

Referring to Figure 4 there is shown therein a further embodiment involving a somewhat difierent arrangement of the pumping mechanism; parts corresponding to those of the former figures have been given the same numerals, and since the functions of the parts are similar they are not discussed in detail. However, the structure of Figure 4 is useful in conjunction with a battery of presses and opening 80 is provided for communication between the press bed 16 shown and an adjoining bed which is not shown. Also a cap 81 retained by bolt means at as 83 provides sump 60' and the cap is provided with a suitable seal to the bed at 85.

From the foregoing will be appreciated that the present invention overcomes the difliculties previously observed in connection with maintaining die cushion guides properly lubricated to prevent abnormal wear due to off-center loads. The unreliable lubrication of guideways by greases or by lost-oil systems can be eliminated and, instead, positive, adequate and continuous lubrication is had, thereby reducing wear of the die cushion ways to a minimum which not only increases the life of the die cushion but substantially eliminates the possibility of the die cushion binding during operation, which could occur due to offcenter loading and inadequate lubrication and possibly damaging the die set being employed or causing high scrap loss of the product being produced.

It will be understood that this invention is susceptible to modification in order to adapt it to diiferent usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a press; a bed having an upwardly opening recess therein, a die cushion detachably mounted in said recess comprising a lower guide member and an upper cylindrical portion slidably fitting over said guide member, vertically extending guides spaced about said recess and vertically extending guide elements spaced about said upper member engaging the said guides in said recess to locate and guide said upper member in vertical reciprocal movement within said recess, an oil sump in said recess, a pump comprising a cylinder portion stationarily mounted in said recess and a plunger portion extending therein and connected with said upper portion, said cylinder portion consisting of an inlet check valve in said sump and said plunger portion comprising an outwardly opening discharge check valve, conduit means leading from the discharge side of said outlet check valve to said guide elements whereby movement of said upper member will supply lubrication to the guide elements, and means for returning the lubricant supplied to said sump.

2. In a press; a bed having an upwardly opening recess therein, a die cushion detachably mounted in said recess, comprising a lower guide portion resting on the bottom wall of the recess and an upper cylindrical portion slidably fitting over said guide portion, the upper end of said cylindrical portion comprising a platen, inter-engaging guide elements arranged about said platen and said recess to guide said platen, a channel formed in said platen communicating with said guide elements, a lubricant sump in said recess, a pump having a part fixed t0 the part in said recess and a part fixed to said cylindrical portionoperable to pump lubricant from said sump to said channel upon vertical movement of the cylindrical portion of the die cushion in said recess, and a member mounted on said platen enclosing said channel means.

3. In combination with a die cushion having guide means about the periphery thereof, channel means on the top of said die cushion communicating with said guide means, a lubricant pump communicating with said channel means operable by movement of the said die cushion during a work cycle, and a top plate mounted on the top of said die cushion and covering said channel.

4. In combination with a die cushion having guide means about the periphery thereof, channel means on the top of said die cushion communicating with said guide means, a lubricant pump communicating with said chan nel means operable by movement of the said die cushion during a work cycle, and a top plate mounted on the top of said die cushion and covering said channel, said plate comprising a drain groove extending thereby and means for draining said drain groove to a point external of said recess.

5. In a press: a reciprocable die cushion, Wall means defining a Well, said die cushion being positioned in said Well, a vertically extending conduit carried by said die cushion, said die cushion having a collection area for fluid in an upper portion thereof and another vertically extending conduit supported in the Well and receiving said first conduit slidably therein, a source of fluid communicating with said second conduit, and valves in the conduits arranged to pass fluid from the source to the collection area upon reciprocating movement of the die cushion, said die cushion comprising an inner and outer cylinder having a spacing therebetween and channel means communicating said spacing with said collection area for the flow of fluid to said spacing.

References Cited in the file of this patent UNITED STATES PATENTS Strand Oct. 5, 1920 Gruss Aug. 16, 1921 Ruggles Oct. 1, 1929 Byerlein Aug. 1, 1933 Schloz Nov. 21, 1933 Hothersall Apr. 6, 1937 Hart July 4, 1939 Jackson Aug. 17, 1948 Wissman Nov. 15, 1949 Allin July 25, 1950 Hoenig Nov. 16, 1954 FOREIGN PATENTS France Mar. 31, 1954 

